• Clean Technology
• /
• v.30 no.3
• /
• pp.203-210
• /
• 2024

This study investigated the optimal conditions for efficiently removing caffeine from green coffee beans using supercritical fluid extraction while preserving the key flavor compounds, trigonelline and chlorogenic acid. The results of the experiments conducted under various pretreatment and supercritical fluid extraction conditions revealed that the highest caffeine extraction rate was 90.6% and it was achieved when green coffee beans with a moisture content of 35% were soaked in hot water. However, this condition also showed a tendency to slightly reduce the retention rates of trigonelline and chlorogenic acid. In the supercritical fluid extraction time experiments, the caffeine content decreased as the extraction time increased. Furthermore, extraction at a temperature of 60 ℃ and a pressure of 40 MPa was the most effective in terms of both caffeine removal and flavor compound preservation. As the amount of water added increased, the caffeine extraction rates increased, but there was also an increase in the loss of flavor compounds. With an increase in the solvent-to-material ratio, the caffeine removal rates improved. The optimal results were observed at a ratio of 250, which achieved a caffeine extraction rate of 91.0% and retention rates of trigonelline and chlorogenic acid of 99.9% and 85.9%, respectively.

• Food Science and Preservation
• /
• v.30 no.3
• /
• pp.492-501
• /
• 2023

In this study, we wanted to understand the impact of different decaffeination processes on aroma compounds of coffee. Therefore, we analyzed differences in physical characteristics and volatile aroma compounds profiles of regular coffee (RC), Swiss water process decaffeinated coffee (SWDC), and supercritical CO₂ decaffeinated coffee (SCDC) after roasting the coffee beans. The electronic nose analysis identified RC and SCDC as different groups which indicates that these groups volatile aroma compound compositions were different. The principal component analysis of volatile compound patterns identified using an electronic nose indicated that there was a large difference in volatile compounds between RC, which was not decaffeinated, and both decaffeinated SWDC and SCDC. The major aroma compounds of RC, SWDC and SCDC were propan-2-one and hexan-2-one which are ketone, and hexanal and (E)-2-pentenal which are aldehyde and 3-methyl-1-butanol which is an alcohol. After roasting, the composition of major volatile compounds appearing in the beans was similar, but the relative odor intensity was different. We identified 28 volatile aroma compounds from RC, SWDC, and SCDC using headspace-solid phase microextraction-gas chromatography/mass spectrometry (HS-SPME-GC/MS), and analyzed 10 major compounds that were present in high abundance, including furfural, 2-furanmethanol, 2,5-dimethylpyrazine, and 2-ethyl-3-methylpyrazine.